A Gordon Conference on RNA editing is planned for January 24-29, 1999 at the Doubletree hotel in Ventura, California. RNA editing is the co- or post-transcriptional modification of RNA which results in the insertion, deletion or substitution of nucleotides. RNA editing can therefore correct, extend or diversify the information encoded within the corresponding genomic sequence and can dramatically alter the function of the modified RNAs. For example, editing events within the mammalian central nervous system can increase the diversity of neurotransmitter receptor expression and ser e to effectively modulate neuronal signaling pathways. Equally significant is the cellular regulation of many of the RNA editing processes which provides for developmental, tissue-specific and metabolic fine tuning of protein function and biochemical pathways. Our understanding of molecular mechanisms underlying RNA editing and their biological occurrence has reached a critical stage where cross-fertilization of hypotheses and experimental approaches is essential for focus in the next decade of research. There are many common questions and experimental goals among investigators of RNA editing despite the diversity of organisms wherein editing occurs, and the apparent dissimilarities in sequences which are modified. Important to the understanding of every editing system is a basic description of the RNA substrates that are modified by these processes. Similarly, questions of general interest concerning the mechanism, specificity, fidelity and processivity of RNA editing can be addressed with a combination of biochemical and molecular biological techniques coupled with the development of in vitro editing systems. In this regard the cis-active regulatory elements and trans-acting factors mediating a number of editing processes are being evaluated at both the molecular and enetic level. Understanding the structure and function of these factors at the level of common or divergent features among the different editing systems is an important goal of the proposed Gordon Research Conference. Still other editing systems have yet to advance to in vitro systems or have been described only recently. The Gordon Research Conference will foster information and technology transfer which will promote developments in these areas. The cellular and molecular aspects of RNA editing regulation are also broadly being pursued at the level of evolution as well as the occurance of editing activities in different tissues and during development. The biological significance of RNA editing is a recurring theme throughout all aspects of the proposed conference. Finally, information about other forms of RNA processing is likely to have implications for understanding RNA editing mechanisms, and vice versa. Investigators working in other areas of RNA processing therefore will participate in appropriate sessions to stimulate exchange between these related fields.